The present invention relates to an accelerometer with a seismic mass which exerts intertial forces on at least one electromechanical transducer under the influence of accelerations.
Known accelerometers of this kind comprise between a mounting base and the seismic mass of the accelerometer an element sensitive to pressure, preferably a piezoelectric transducer element. These transducer elements are generally in the form of flat-shaped disks which are polarized in the same direction as the force to be measured. The surface of the electrodes for deriving the charges produced are perpendicular to the direction of polarization, i.e., to the direction of pressure.
Similar accelerometers with transducer elements strained to shear, more particularly piezoelectric elements, are known. In this case, the elements are flat or annular-shaped and they are polarized in parallel with the direction of the force to be measured. The surface of the electrodes which derive the charges produced, are oriented in parallel with the direction of polarization, respectively the direction of shear. In the case of annular elements, the polarization and the direction of the force to be measured is mostly axial.
All known accelerometers use pressure or shear strains which act over the full section of the transducer element. Such transducers are relatively sensitive to external influences, e.g. electric or electromagnetic fields which may induce disturbing signals in the electrodes.